I was meditating today on accepting and letting go of fear, anger and anxiety (which were very loud in my mind at the time) when suddenly my reactions to these states turned into disgust: whenever anger came up, I quickly became disgusted by it. Same thing happened for fear and anxiety. As soon as I sense the suffering in my thoughts, I become disgusted by them. Why is this happening?
Why is this happening? The mind could be becoming clear & attuned to what is healthy & peaceful. Inner wisdom could be functioning.
Below is a quote from The Removal of Distracting Thoughts sutta:
Like a well-dressed young man or woman who feels horrified, humiliated and disgusted because of the carcass of a snake, dog or human that is hung round his or her neck...the monk in whom unskillful thoughts continue to arise...ponders on the disadvantages of unskillful thoughts thus: Truly, these thoughts of mine are unskillful, blameworthy and productive of misery. Then the evil, unskillful thoughts are eliminated; they disappear. By their elimination, the mind stands firm, settles down, becomes unified and concentrated, just within (his subject of meditation).
The Fire Sermon describes the liberation that results from clearly seeing the 'fire', burning or oppressiveness of lust, hatred & delusion. In the text, the word translated as "estrangement" is 'nibbindaṃ', which also means 'disgust' or 'revulsion'.
The quote below explains the word 'nibbindaṃ':
The more common translation of nibbidā is “disillusionment, disenchantment” but the more serious spiritual practitioners generally prefer “revulsion,” even “disgust.”
In some commentaries, 'nibbindaṃ-disgust' (nibbidanupassana-nana) precedes or creates the 'desire for liberation' (muncitukamyata-nana) rather than liberation itself (as found in the scriptures).
Note: 'Disgust' is not the same as 'hatred/aversion'. 'Disgust' leads to freedom, since it leads to the rejecting, dropping & subsiding of the negative emotion.
The Buddha said that all suffering is caused by craving, which is also interpreted as attachment. Your meditation started out as letting go of these afflictive emotions, which you were clinging to as evidenced by the loud noises in your mind. It was a good start, but what happened is rather than letting go you flipped to the polar opposite of attachment, which is aversion. This is not an uncommon event when one is trying to cope with afflictive emotions. Our conceptual mind outside of Buddhism has learned that what we do not like/love we must dislike/hate. Your meditative practice needs to find the middle...and I do not mean apathy...rather that you neither like nor dislike these emotions; that they do not influence your life in any positive way, and that you can let go of them without acting on or reacting to them in any manner. They will still crop up on occasion, so repeat the process until you can go through life without any need for these emotions to arise. Lama Surya Das devotes a large section of his book, "Awakening the Buddha Within", to meditation training.